A judge called for an end to a "medieval turf war" on the streets of London as he jailed a hit man for at least 38 years for murdering a gang boss and then shooting his accomplice.

Jamie Marsh-Smith, 23, who was known as Freddy after the Nightmare on Elm Street film character, was hired to kill Zafer Eren, of the Tottenham Turks gang, by rivals the Hackney Turks.

Days after the murder in April last year, Marsh-Smith then tried to kill his getaway driver and co-defendant, Samuel Zerei.

Following an Old Bailey trial, Marsh-Smith, of Manor House, north London, was found guilty of murder and two attempted murders. Zerei, 21, of Newington Green, north London, was found guilty of murder.

The pair sat in the dock flanked on all sides by security guards as judge John Bevan QC sentenced them. He said the murder was part of a long-standing feud between warring Turkish gangs that had resulted in 26 incidents, a number of them involving guns.

Calling for the families to end the fighting, the judge said: "The use of the streets of this city for fighting a medieval turf war using hired hands as hit men is as intolerable as it is unacceptable."

Marsh-Smith was jailed for life with a minimum term of 38 years for murder and 30 years for each of the attempted murders to run concurrently.

The judge told Marsh-Smith: "You are a callous, unfeeling and highly dangerous young man prepared to kill for what I suspect is a modest fee."

As he jailed Zerei for life with a minimum term of 28 years, the judge told him: "If you are operating in circles of violence you cannot complain when you become a victim of it yourself."

Zerei's lawyer, Pavlos Panayi QC, said the fact his client had been shot himself was a mitigating factor in his crime and that he was now a "marked man" in prison.

He said: "A key fact in his case is that as a consequence of the part Samuel Zerei played on the 18 April he found himself with bullets in his arm and a grazing bullet to his neck lying on the floor facing Mr Marsh-Smith and with a gun pointing at him. During the moments that followed he expected to die. He was sure he was about to be shot in the face and killed."

He added: "It is pure luck that Samuel Zerei is here today. He knows directly what the consequences of gang-related violence are."

During the trial, prosecutor Edward Brown QC said the violence dated back to December 2012 when Marsh-Smith tried to kill the murdered gangster's cousin, Inan Eren, on his doorstep.

Then Marsh-Smith shot dead Zafer Eren as he went into the block of flats in Southgate where he lived. The masked gunman fired seven shots and hit him three times in the back before walking to his getaway car. Marsh-Smith then targeted his getaway driver, Zerei, who "knew the truth", Mr Brown said.

The lawyer said: "Zerei was the driver of that car and the gunman he drove to and from the scene, and sat with for an hour as they waited for Zafer Eren to come home, was Marsh-Smith."

Zerei suffered gunshot wounds in Markfield Park, Tottenham, but survived the attack and managed to text his brother to alert him to who had shot him.

Marsh-Smith had been recruited by the Turkish gangsters because he came from outside their community and would not be suspected by the police. Following the case, Scotland Yard said it was still trying to catch those responsible for ordering the hit on Eren.

The senior investigating officer, DCI Noel McHugh, said: "The conduct of Jamie Marsh-Smith and Samuel Zerei reads like something from a film. They accepted a contract to kill; they had no known dispute with their victim. Marsh-Smith and Zerei were professional and dangerous criminals. Marsh-Smith even tried to execute his getaway driver Samuel Zerei when he failed to dispose of the getaway car used in the murder of Zafer Eren.

"This investigation has been brought about through truly outstanding and painstaking detective work, piecing together a complex evidential jigsaw. Our investigation continues into Zafer Eren's murder as we seek to find those responsible for ordering the killing. The convictions today demonstrate that the police will not go away. Police are offering a reward of up to £30,000 for information leading to the arrest and conviction of those responsible for Zafer Eren's murder."

On Friday, Marsh-Smith's half brother, Wayne McNeish, was jailed for four-and-a-half years for perverting the course of justice by helping Marsh-Smith to evade police. He had denied the charge.

Following the sentencing, Zafer Eren's wife said: "This has had a devastating impact on our life; our baby was only 26 days old when Zafer was killed on my doorstep. Marsh-Smith and Zerei have shown no remorse for their actions."

Last week, the jury failed to reach verdicts on two further defendants accused of the attempted murder of Inan Eren. Christopher Annan, 23, and Tyrone Wright, 19, await a decision on whether they will face a retrial.

The CPS London chief crown prosecutor, Baljit Ubhey, said: "Gang crime is a significant driver of violent crime in the capital and I am committed to tackling this menacing form of offending. This case represents just one of a long list of incidents of gang war between the Tottenham Turks and the Hackney Turks in north London.

"These two gangs have been feuding for at least five years and their mutual hatred has caused unnecessary pain and bloodshed on both sides. The war between these gangs has resulted in murder, attempted murder, beatings, threats and damage to shops and clubs belonging to those perceived to be associated with them. In this latest episode of violence the victims were targeted on their own doorsteps."